The Greening Process in Euglena gracilis, I. The Kinetics of Appearance of Chloroplast Proteins and the Effect of Cycloheximide and Chloramphenicol on Their Synthesis

Abstract

Abstract Proplastids in dark grown Euglena gracilis cells undergo a developmental process during illumination yielding full functional chloroplasts. The appearance of chlorophyll, cytochrome 552, cytochrome 563, and ribulose-1,5-bisphosphate carboxylase in these cells was investigated and different kinetics of synthesis were observed for each component. Light adaptation experiments on dark grown cells in the presence of the 70S ribosome in­ hibitor, chloramphenicol, revealed that the synthesis of cytochrome 552 was blocked but not cytochrome 563. In presence of the 80S ribosome inhibitor cycloheximide, the synthesis of both cytochromes as well as of chlorophyll (a + b) and of ribulose-1,5-bisphosphate carboxylase were inhibited. However, at low concentrations of cycloheximide (3.5 to 9 x 10-8 ᴍ), a stimulation of the synthesis per cell of the cytochromes, of chlorophyll (a + b) and of ribulose-1,5-bisphosphate carboxylase was observed.